Fix typo in tx_head.nim delta calculator

why:
  Causes havoc in most bit fringe cases.

details:
  When setting the head forward, the delta was wrongly registered from
  the static "left" end (which limits the loop) rather than the moving
  "right" end.

nimbus/utils/tx_pool.nim

@@ -600,6 +600,10 @@ proc jobDeltaTxsHead*(xp: TxPoolRef; newHead: BlockHeader): bool
 
     # Re-inject transactions, do that via job queue
     if 0 < changes.addTxs.len:
+      debug "queuing delta txs",
+        mode = "inject",
+        num = changes.addTxs.len
+
       discard xp.job(TxJobDataRef(
         kind:       txJobAddTxs,
         addTxsArgs: (
@@ -608,6 +612,10 @@ proc jobDeltaTxsHead*(xp: TxPoolRef; newHead: BlockHeader): bool
 
     # Delete already *mined* transactions
     if 0 < changes.remTxs.len:
+      debug "queuing delta txs",
+        mode = "remove",
+        num = changes.remTxs.len
+
       discard xp.job(TxJobDataRef(
         kind:       txJobDelItemIDs,
         delItemIDsArgs: (

nimbus/utils/tx_pool/tx_tasks/tx_head.nim

@@ -164,8 +164,10 @@ proc headDiff*(xp: TxPoolRef;
     #                   |       |
     #                  new  << current (step back this one)
     #
-    # preserve transactions on the upper branch block numbers
-    # between #new..#current to be re-inserted into the pool
+    # + preserve transactions on the upper branch blocks,
+    #
+    # + txs of blocks with numbers between #new..#current need to be
+    #   re-inserted into the pool
     #
     while newHead.blockNumber < curBranchHead.blockNumber:
       xp.insert(txDiffs, curBranchHash)
@@ -190,11 +192,13 @@ proc headDiff*(xp: TxPoolRef;
     #                   |       |
     #              current  << new (step back this one)
     #
-    # preserve transactions on the upper branch block numbers
-    # between #current..#new to be deleted from the pool
+    # + preserve some transactions on the upper branch blocks,
+    #
+    # + txs of blocks with numbers between #current..#new need to be
+    #   deleted from the pool (as they are on the block chain, now)
     #
     while curHead.blockNumber < newBranchHead.blockNumber:
-      xp.remove(txDiffs, curBranchHash)
+      xp.remove(txDiffs, newBranchHash)
       let
         tmpHead = newBranchHead # cache value for error logging
         tmpHash = newBranchHash

tests/test_txpool.nim

@@ -905,8 +905,9 @@ proc txPoolMain*(noisy = defined(debug)) =
   noisy.runTxLoader
   noisy.runTxPoolTests
   noisy.runTxPackerTests
-  test_txpool2.runTxPoolCliqueTest()
-  test_txpool2.runTxPoolPosTest()
+  runTxPoolCliqueTest()
+  runTxPoolPosTest()
+  noisy.runTxHeadDelta
 
 when isMainModule:
   const
@@ -922,8 +923,9 @@ when isMainModule:
   noisy.runTxPoolTests
   noisy.runTxPackerTests
 
-  #runTxPoolCliqueTest()
-  #runTxPoolPosTest()
+  runTxPoolCliqueTest()
+  runTxPoolPosTest()
+  noisy.runTxHeadDelta
 
   #noisy.runTxLoader(dir = ".")
   #noisy.runTxPoolTests

tests/test_txpool2.nim

@@ -6,7 +6,7 @@ import
   ../nimbus/p2p/chain,
   ../nimbus/p2p/clique/[clique_sealer, clique_desc],
   ../nimbus/[chain_config, config, genesis, transaction, constants],
-  ../nimbus/utils/[tx_pool],
+  ../nimbus/utils/tx_pool,
   ./test_txpool/helpers,
   ./macro_assembler
 
@@ -234,11 +234,11 @@ proc runTxPoolPosTest*() =
 #runTxPoolPosTest()
 
 
-proc runTxMissingTxNoce*(noisy = true) =
+proc runTxHeadDelta*(noisy = true) =
   ## see github.com/status-im/nimbus-eth1/issues/1031
 
-  suite "TxPool: Issue #1031":
-    test "Reproducing issue #1031":
+  suite "TxPool: Synthesising blocks (covers issue #1031)":
+    test "Packing and adding multiple blocks to chain":
       var
         env = initEnv(some(100.u256))
         xp = env.xp
@@ -266,9 +266,10 @@ proc runTxMissingTxNoce*(noisy = true) =
 
           xp.jobCommit()
 
-          noisy.say "***", "stats",
+          noisy.say "***", "txDB",
             &" n={n}",
-            &" pending/staged/packed:total/disposed={xp.nItems.pp}"
+            # pending/staged/packed : total/disposed
+            &" stats={xp.nItems.pp}"
 
           xp.prevRandao = prevRandao
           var blk = xp.ethBlock()
@@ -285,15 +286,27 @@ proc runTxMissingTxNoce*(noisy = true) =
             transactions: blk.txs,
             uncles: blk.uncles)
 
-          let rr = chain.persistBlocks([blk.header], [body])
-          check rr.isOk
+          # Commit to block chain
+          check chain.persistBlocks([blk.header], [body]).isOk
 
-          # PoS block canonical head must be explicitly set using setHead
+          # PoS block canonical head must be explicitly set using setHead. The
+          # function `persistHeaderToDb()` used in `persistBlocks()` does not
+          # reliably do so due to scoring.
           chainDB.setHead(blk.header)
 
-          discard xp.jobDeltaTxsHead(blk.header)
+          # Synchronise TxPool against new chain head, register txs differences.
+          # In this particular case, these differences will simply flush the
+          # packer bucket.
+          check xp.jobDeltaTxsHead(blk.header)
+          check xp.nJobs == 1
+
+          # Move TxPool chain head to new chain head and apply delta jobs
           xp.head = blk.header
           xp.jobCommit()
+          check xp.nItems.staged == 0
+          check xp.nItems.packed == 0
+
+          setErrorLevel() # in case we set trace level
 
       check chainDB.currentBlock == 10.toBlockNumber
       head = chainDB.getBlockHeader(chainDB.currentBlock)
@@ -311,7 +324,7 @@ when isMainModule:
 
   setErrorLevel() # mute logger
 
-  runTxPoolCliqueTest()
-  runTxPoolPosTest()
+  #runTxPoolCliqueTest()
+  #runTxPoolPosTest()
 
-  true.runTxMissingTxNoce
+  true.runTxHeadDelta